Rotatable cartridge with a metering chamber for analyzing a biological sample

ABSTRACT

An automatic analyzer cartridge, spinnable around a rotational axis, has aliquoting and metering chambers, a connecting duct there between, and a vent connected to the metering chamber and nearer to the rotational axis than the metering chamber. The metering chamber has side walls that taper away from a central region. Capillary action next to the side walls is greater than in the central region. A circular arc about the rotational axis passes through a duct entrance in the aliquoting chamber and a duct exit in the metering chamber. The cartridge has a downstream fluidic element which is part of a fluidic structure for processing a biological sample into the processed biological sample. A valve connects the metering chamber to the fluidic element, which is fluidically connected to the fluidic structure. The fluidic structure receives the biological sample and has a measurement structure for enabling measurement of the processed biological sample.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/352,680 filed Nov. 16, 2016, which is a continuation of InternationalApplication No. PCT/EP2015/063779 filed Jun. 18, 2015, which claimspriority to European patent application No. EP14171426.1, filed Jun. 6,2014.

TECHNICAL FIELD

The inventive embodiments disclosed herein relate to analytical testdevices for biological samples, in particular to the design and use ofrotatable cartridges for performing a measurement of a biologicalsample.

BACKGROUND AND RELATED ART

Two classes of analysis systems are known in the field of medicalanalysis: wet analysis systems, and dry-chemical analysis systems. Wetanalysis systems, which essentially operate using “wet reagents” (liquidreagents), perform an analysis via a number of required step such as,for example, providing a sample and a reagent into a reagent vessel,mixing the sample and reagent together in the reagent vessel, andmeasuring and analyzing the mixture for a measurement variablecharacteristic to provide a desired analytical result (analysis result).Such steps are often performed using technically complex, large,line-operated analysis instruments, which allow manifold movements ofparticipating elements. This class of analysis system is typically usedin large medical-analytic laboratories.

On the other hand, dry-chemical analysis systems operate using “dryreagents” which are typically integrated in a test element andimplemented as a “test strip”, for example. When these dry-chemicalanalysis systems are used, the liquid sample dissolves the reagents inthe test element, and the reaction of sample and dissolved reagentresults in a change of a measurement variable, which can be measured onthe test element itself. Above all, optically analyzable (in particularcolorimetric) analysis systems are typical in this class, in which themeasurement variable is a color change or other optically measurablevariable. Electrochemical systems are also typical in this class, inwhich an electrical measurement variable characteristic for theanalysis, in particular an electrical current upon application of adefined voltage, can be measured in a measuring zone of the test elementusing electrodes provided in the measuring zone.

The analysis instruments of the dry-chemical analysis systems areusually compact, and some of them are portable and battery-operated. Thesystems are used for decentralized analysis, for example, at residentphysicians, on the wards of the hospitals, and in so-called “homemonitoring” during the monitoring of medical-analytic parameters by thepatient himself (in particular blood glucose analysis by diabetics orcoagulation status by warfarin patients).

In wet analysis systems, the high-performance analysis instruments allowthe performance of more complex multistep reaction sequences (“testprotocols”). For example, immunochemical analyses often require amultistep reaction sequence, in which a “bound/free separation”(hereafter “b/f separation”), i.e., a separation of a bound phase and afree phase, is necessary. According to one test protocol, for example,the probe can first be transported through a porous solid matrix, whichcontains a specific binding reagent for the analyte. A marking reagentcan subsequently be caused to flow through the porous matrix, to markthe bound analyte and allow its detection. To achieve precise analysis,a washing step must be performed, in which unbound marking reagent iscompletely removed. Numerous test protocols are known for determiningmanifold analytes, which differ in manifold ways, but which share thefeature that they require complex handling having multiple reactionsteps, in particular also a b/f separation possibly being necessary.

Test strips and similar analysis elements normally do not allowcontrolled multistep reaction sequences. Test elements similar to teststrips are known, which allow further functions, such as the separationof red blood cells from whole blood, in addition to supplying reagentsin dried form. However, they normally do not allow precise control ofthe time sequence of individual reaction steps. Wet-chemical laboratorysystems offer these capabilities, but are too large, too costly, and toocomplex to handle for many applications.

To close these gaps, analysis systems have been suggested which operateusing test elements which are implemented in such a manner that at leastone externally controlled (i.e., using an element outside the testelement itself) liquid transport step occurs therein (“controllable testelements”). The external control can be based on the application ofpressure differences (overpressure or low-pressure) or on the change offorce actions (e.g., change of the action direction of gravity byattitude change of the test element or by acceleration forces). Theexternal control is especially frequently performed by centrifugalforces, which act on a rotating test element as a function of thevelocity of the rotation.

Analysis systems having controllable test elements are known andtypically have a housing, which comprises a dimensionally-stable plasticmaterial, and a sample analysis channel enclosed by the housing, whichoften comprises a sequence of multiple channel sections and chambersexpanded in comparison to the channel sections lying between them. Thestructure of the sample analysis channel having its channel sections andchambers is defined by profiling of the plastic parts. This profiling isable to be generated by injection molding techniques or hot stamping.Microstructures, which are generated by lithography methods,increasingly being used more recently, however.

Analysis systems having controllable test elements allow theminiaturization of tests which have only been able to be performed usinglarge laboratory systems. In addition, they allow the parallelization ofprocedures by repeated application of identical structures for theparallel processing of similar analyses from one sample and/or identicalanalyses from different samples. It is a further advantage that the testelements can typically be produced using established production methodsand that they can also be measured and analyzed using known analysismethods. Known methods and products can also be employed in the chemicaland biochemical components of such test elements.

In spite of these advantages, there is a further need for improvement.In particular, analysis systems which operate using controllable testelements are still too large. The most compact dimensions possible areof great practical significance for many intended applications.

United States patent U.S. Pat. No. 8,114,351 B2 discloses an analysissystem for the analysis of a body fluid sample for an analyte. Theanalysis system provides a test element and an analysis instrumenthaving a dosing station and a measurement station. The test element hasa housing an (at least) one sample analysis channel enclosed by thehousing. The test element is rotatable around an axis of rotation whichextends through the test element.

U.S. Pat. No. 8,470,588 B2 discloses a test element and a method fordetecting an analyte. The test element is essentially disk shaped andflat, and can be rotated about a preferably central axis which isperpendicular to the plane of the disk shaped test element.

Kim, Tae-Hyeong, et al. “Flow-enhanced electrochemical immunosensors oncentrifugal microfluidic platforms.” Lab on a Chip 13.18 (2013):3747-3754, doi:10.1039/c3Ic50374g, (hereafter “Kim et. al.”) discloses afully integrated centrifugal microfluidic device with features fortarget antigen capture from biological samples, via a bead-basedenzyme-linked immune-sorbent assay, and flow-enhanced electrochemicaldetection. This is integrated into a Centrifugal microfluidic discs,also known as “lab-on-a-disc” or microfluidic CDs.

Martinez-Duarte, Rodrigo, et al. “The integration of 3D carbon-electrodedielectrophoresis on a CD-like centrifugal microfluidic platform.” Labon a Chip 10.8 (2010): 1030-1043, doi:10.1039/B925456K, (hereafter“Martinez-Duarte et. al.”) discloses a dielectrophoresis (DEP)-assistedfilter with a compact disk (CD)-based centrifugal platform. 3D carbonelectrodes are fabricated using the C-MEMS technique and are used toimplement a DEP-enabled active filter to trap particles of interest.

European patent application publication EP 2 302 396 A1 discloses ananalyzing device includes: an operation cavity that is adjacent to afirst reserving cavity retaining a sample liquid, in a circumferentialdirection of rotational driving; a connecting section provided on a sidewall of the first reserving cavity to suck the sample liquid by acapillary force and transfer the sample liquid to the operation cavity;and second reserving cavities that are disposed outside the operationcavity in the circumferential direction of the rotational driving andcommunicate with the outermost position of the operation cavity througha connecting passage. The connecting section is circumferentiallyextended farther than the liquid level of the sample liquid retained inthe first reserving cavity.

United States patent application publication US 2009/0246082 disclosesan analysis device comprising a separation chamber for separating asample solution into a solution component and a solid component, aholding channel for holding a predetermined amount of the separatedsolid component, a mixing chamber connected to the holding channel, anoverflow channel connected between the holding channel and theseparation chamber, a sample overflow chamber into which the samplesolution remaining in the separation chamber is discharged, and a jointchannel connecting the separation chamber and the sample overflowchamber. After the separated solution component fills the overflowchannel with priority by a capillary force, the separated solidcomponent is transferred to the holding channel via the overflowchannel, and a predetermined amount of the solid component is measured.The solid component in the holding channel is transferred to the mixingchamber by a centrifugal force, and simultaneously, the sample solutionremaining in the separation chamber is discharged to the sample overflowchamber by the siphon effect of the joint channel.

SUMMARY

A method of performing a measurement on a processed biological sampleusing the cartridge, a cartridge for an automatic analyzer, and anautomatic analyzer are disclosed in the independent claims. Additionalembodiments are given in the dependent claims.

In one aspect of the invention, an embodiment provides for a method ofperforming a measurement of a processed biological sample using acartridge.

A cartridge as used here encompasses also any test element forprocessing the biological sample into a processed biological sample. Thecartridge may include structures or components which enable ameasurement to be performed on the biological sample. A cartridge is atest element as is defined and explained in U.S. Pat. Nos. 8,114,351 B2and 8,470,588 B2. A cartridge as used herein may also be referred to asa Centrifugal microfluidic disc, also known as “lab-on-a-disc” or amicrofluidic CD.

A biological sample as used herein encompasses as chemical productderived, copied, replicated, or reproduced from a sample taken from anorganism.

The cartridge is operable for being spun around a rotational axis. Thecartridge comprises an aliquoting chamber. The cartridge furthercomprises a metering chamber. The cartridge further comprises aconnecting duct for connecting the metering chamber with the aliquotingchamber. The connecting duct comprises a duct entrance in the aliquotingchamber. The connecting duct further comprises a duct exit in themetering chamber. A circular arc about or drawn about the rotationalaxis would pass through both the duct entrance and the duct exit. Anequivalent statement would be that connecting the duct exit and the ductentrance are roughly or approximately equidistant to the rotationalaxis.

The cartridge further comprises a downstream fluidic element. Thedownstream fluidic element is connected to the metering chamber via avalve. The downstream fluidic element is downstream to the meteringchamber. There is a flow of fluid from the metering chamber to thedownstream fluidic element.

The cartridge further comprises a fluidic structure for processing abiological sample into the processed biological sample. The fluidicstructure comprises the downstream fluidic element. The downstreamfluidic element is fluidically connected to the fluidic structure. Thedownstream fluidic element is a component or a part of the fluidicstructure. The fluidic structure comprises a measurement structure forenabling measurement of the processed biological sample. The fluidicstructure is configured for receiving the biological sample. Forinstance the cartridge may have an entrance receptacle adapted forreceiving the biological sample.

The method comprises the step of placing the biological sample into thefluidic structure. The method further comprises the step of controllingthe rotational rate of the cartridge to process the biological sampleinto the processed biological sample using the fluidic structure. Themethod further comprises filling the aliquoting chamber with a fluid. Insome examples the aliquoting chamber has fluid added directly to it, forexample with a pipette or other dispenser. In other embodiments there isa reservoir which opens into the aliquoting chamber. In yet otherembodiments there may be another container or reservoir within thecartridge that contains the fluid and then this fluid is emptied ordispensed into the aliquoting chamber. The method further comprises thestep of decreasing the rotational rate of the cartridge to permit orforce the fluid in the aliquoting chamber to flow into the connectingduct and to fill the metering chamber for a first time. The decrease inthe rotational rate of the cartridge may cause the fluid to move withinthe aliquoting chamber. For instance a rapid deceleration of the fluidmay be used to splash the fluid in the direction of the connecting duct.

The method further comprises increasing the rotational rate of thecartridge to transfer a first part of the fluid from the meteringchamber through the valve and to transfer a first remaining part backinto the aliquoting chamber. In some examples the fluid may be drawninto the metering chamber by capillary forces. The decrease in therotational rate may cause the fluid to splash or move against theconnecting duct and then the capillary forces may then fill the meteringchamber. Increasing the rotational rate of the cartridge to transfer thefirst part of the fluid may have the effect of also cancelling anycapillary forces which are drawing fluid into the metering chamber.

The method further comprises the step of decreasing the rotational rateof cartridge to permit or force the fluid in the reservoir to flow intothe metering chamber and to fill the metering chamber a second time.This is a repetition of the second to last step. The method furthercomprises increasing the rotational rate of the cartridge to transfer asecond part of the fluid from the metering chamber through the valve andto transfer a second remaining part back into the aliquoting chamber.This and the subsequent steps illustrate that the metering chamber andaliquoting chamber may be used to fill and empty the metering chambermultiple times and thereby provide fluid parts multiple times to thedownstream fluidic element.

And finally the method comprises performing the measurement using themeasurement structure and using a measurement system. This method mayhave the advantage that the fluid can be transferred from the aliquotingchamber multiple times to the downstream fluidic element. In someexamples the measurement is an optical measurement. The measurement mayinclude, but is not limited to: a photometric transmission measurement,a measurement of the scattering of light, a chemiluminescence, afluorescence, and electrochemiluminescense (ECL) measurement.

In some examples the first part of the fluid and the second part of thefluid have the same volume. In further embodiments the first remainingpart and the second remaining part both have the same volume.

It should be noted that the aliquoting chamber and metering chamberdescribed above may be used to dispense a part of the fluid multiplenumbers of times.

In one example the aliquoting chamber has a depth of approximately 2.5mm and a width of 4.0 mm. The height in the radial direction (towardsthe axis of rotation) may be 7 mm.

In one example the metering chamber may have depth of 0.8 mm and a widthof 3.5 mm. The height without the expansion chamber may be approximately7.0 mm.

In another embodiment, the metering chamber has side walls and a centralregion. The side walls taper away from the central region. Capillaryaction next to the side walls of the metering chamber is greater than inthe central region of the metering chamber.

In another embodiment the cartridge further comprises a vent which isconnected to the metering chamber. The vent is nearer to the rotationalaxis than the metering chamber. The vent for example may be connectedsuch that gas is able to enter or exit the metering chamber. This mayenable fluid to enter or exit the metering chamber.

In another embodiment, the cartridge further comprises an expansionchamber with a vent. The expansion chamber is connected to the meteringchamber. The capillary action in the metering chamber is greater thancapillary action in the expansion chamber. The expansion chamber isnearer to the rotational axis than the metering chamber

In another embodiment the interface between the metering chamber and theexpansion chamber is formed as a capillary valve or a capillary stopvalve. In this embodiment the cross section of the metering chamberincreases step like towards the larger cross section of the expansionchamber. Thereby the fluid will not flow from the metering chamber intothe expansion chamber if no additional forces are applied.

The expansion chamber is nearer to the rotational axis than the meteringchamber

Capillary action as used herein may also refer to capillarity, capillarymotion, or wicking, or capillary force. Capillary action is the abilityof a liquid to flow in narrow spaces without the assistance of externalforces like gravity or centrifugal forces.

Capillary action is caused by intermolecular forces between the liquidand adjacent solid surfaces. Adhesive forces between the liquid and theadjacent solid surfaces can be used to counteract gravity or otherexternal forces. In some cases the capillary action can be increased bydecreasing the distance between adjacent solid surfaces.

This embodiment may have the advantage that the metering chamber fillsfirst at the side walls surrounding the central region and thereafter atthe central region. This fills the metering chamber in a predictable andcontrollable way that reduces the chances that bubbles will form oradhere.

The formation of bubbles prevent most microfluidic structures from beingused more than once for dispensing a metered amount of fluid. Forexample, the patent application US 2009/0246082 A1 teaches the use ofair holes which are positioned in various locations in an overflowchamber or channel. See for example FIGS. 3, 4, and 5 of US 2009/0246082A1. The chamber of 13 of FIG. 5(a) is essentially a siphon. Thepositioning of an air hole at the bend of a siphons as is depicted inFIG. 5(a) however does not enable the repeatable aliquoting of fluid inthe way that having a metering camber with side walls and a centralregion as described above. This potential advantage is described ingreater detail below.

Similarly an aliquoting structure described in EP 2302396 A1 enablesparallel splitting of fluid in several aliquots, but also uses a ventingstructure that only lets air in at the position nearest to therotational axis. For example see FIG. 55 of EP 2302396 A1 and theaccompanying text. The structure shown in the picture features a longcapillary channel that has to be filled by fluid. The channel featuresseveral vents and connections to downstream chambers.

In FIG. 42, of EP 2302396 A1 a siphon 215b connects a chamber 210b withanother chamber 209c. Placing a vent at the point of siphon 215b closestto the rotational axis 107 would not enable the reliable aliquotation ofthe same amount of fluid every time due to the risk of bubble formation.The structures shown in EP 2302396 has the following drawbacks: Therefilling of such a structure for a second aliquoting step is highlyunreliable. For a second aliquoting step the capillary has to be filledagain. As the walls of the capillary are still wetted the fillingprocess differs from the initial filling process of the first aliquotingstep. The fluid moves significantly faster along the channel walls thanalong the channels center. Due to the small channel diameter fluidprogressing on one channel wall often gets in contact with fluid theother channel wall. This causes the formation of an air bubble thatclogs the channel. This effect is significantly increased if fluids withlow surface tension (e.g. washing buffers) are aliquoted. Theprobability of air bubble formation rises with the length of thecapillary to be filled.

Experiments conducted show that long capillaries cannot be reliably usedin repetitive aliquoting steps. A structure with a single long capillaryand a vent near the bend was constructed. During the tests air bubblesclogged the vent consistently when a second aliquotation of the liquidis attempted.

The present embodiment may have a further advantage by that enablesserial and accurate aliquoting steps. A “closed” capillary with fourwalls can be completely avoided in this structure. In some examples, thefluid may pass the second duct and reach the metering chamber due to theinertia of the fluid by stopping the rotation of the disk with anegative acceleration. In some examples, the second duct does not act ascapillary. In some embodiments, the fluid may pass the second duct andreach the metering chamber due both capillary forces and forces causedby inertia. In the metering chamber the side walls may function asguidance structures at the outer walls guide the fluid due to a highercapillary action than the central region. After the side walls havefilled, the central part of the metering chamber may also fill bycapillary forces. The guidance structure features a “open” capillarystructure comprising three walls preventing air bubble formation oradhesion. The edge of the metering chamber closest to the rotationalaxis borders an expansion chamber. In some examples the central part ofthe metering chamber borders the expansion chamber over its whole width.This may avoid or reduce the risk of air bubble formation in themetering chamber which may enable the precise metering and reliablerefilling of the metering chamber for multiple subsequent aliquotationsusing the same microfluidic structure.

This structure enabled serial aliquoting of three aliquots in 8/8 testeddisks.

In addition to the potential advantages describe above, the fluidicstructure in US 2009/0246082 has the additional disadvantage whencompared to the present embodiment. The overflow chamber 15 (see FIG.5(c) of US 2009/0246082) serves to maintain and hold surplus fluid whichis in contrast to the present embodiment. Surplus fluid will becometrapped in the overflow chamber 15. In the present embodiment, the fluidin the aliquoting chamber may be able to be transferred to the meteringchamber.

In another embodiment the direction of the rotation of the cartridge issuch that the direction of rotation passes through the aliquotingchamber first then the metering chamber. This has the effect that whenthe cartridge is decelerated the fluid is forced up to the connectingduct.

In another embodiment the connecting duct is a funnel which serves tofunnel fluid from the aliquoting chamber to the metering chamber.

In another embodiment the rotational axis of the cartridge is verticalwhen the method is performed.

In another embodiment, the side walls of the metering chamber border theexpansion chamber.

In another embodiment, the side walls has a region closest to therotational axis wherein the region borders to and opens into theexpansion chamber.

In another embodiment, the central region of the metering chamberborders the expansion chamber.

In another embodiment, the central region has a zone closest to therotational axis. wherein the region borders to and opens into theexpansion chamber.

In another embodiment, the measuring chamber has a border between themetering chamber and the expansion chamber. The border is at least 5time longer than the width of the valve.

In another embodiment the valve is a capillary valve or a capillary stopvalve.

A capillary valve or capillary stop value as used herein is a valve orstructure which uses the capillary force of a fluid to prevent fluidfrom flowing through the capillary stop valve. For example a tube with asufficiently small diameter will draw fluid into it and the capillaryforce will prevent the fluid from flowing out of the tube. For the caseof this tube the entrance and exit of the tube function as capillarystop valves. In some examples the duct exit itself may have dimensionssmall enough (compared to the adjacent fluidic structures and chambers)that the duct exit functions as a capillary stop.

In another embodiment the valve is a microvalve which is able to beopened and resealed. For example a paraffin-based valve with an embeddedmicro-heater may be used.

In another example the microvalve may be a valve based on a ferrofluidsuch as is described in Park et al in the article “MultifunctionalMicrovalves Control by Optical Illumination on Nanoheaters and ItsApplication in Centrifugal Microfluidic Devices” in Lab Chip, 2007, 7,pages 557-564.

In another embodiment the fluidic structure is a microfluidic structure.

In another embodiment the step of increasing the rotational rate of thecartridge to transfer a first part of the fluid from the meteringchamber through the valve comprises increasing the rotational rate ofthe cartridge to a first rotational rate to transfer the remaining partof the fluid back to the aliquoting chamber and increasing therotational rate of the cartridge to a second rotational rate to transferthe first part of the fluid from the metering chamber through the valve.When the cartridge is rotated at a higher rate at the first rotationalrate the centrifugal force becomes greater than any capillary forcewhich is drawing fluid into the metering chamber. Fluid is then forcedout of the metering chamber until the fluid level is equal with thelowest level of the duct exit. Increasing to the second rotational ratethen forces the fluid through the valve. In some examples the valve isopen. For example if a ferrofluid or a paraffin-based microvalve isused.

This embodiment may have the benefit of increasing the accuracy of thefluid which is dispensed to the downstream fluidic element. As analternative to this the cartridge is simply rotated at a rate which isfast enough to force the fluid through the valve. This may result in theamount of fluid being transferred to the downstream fluidic element ifthe first and second rotational rates are used. In another alternativeif the valve is a controllably sealable or openable microvalve then thecartridge may be operated at a rotational rate to force the remainingpart of the fluid back into the aliquoting chamber. After this isaccomplished then the microvalve is opened and the rotation forces thefluid from the metering chamber into the downstream fluidic element. Asan alternative it may be possible to replace the microvalve with areusable siphon.

In another embodiment the step of increasing the rotational rate of thecartridge to transfer a second part of the fluid from the meteringchamber through the valve comprises increasing the rotational rate ofthe cartridge to the first rotational rate to transfer the remainingpart of the fluid back to the aliquoting chamber and increasing therotational rate of the cartridge to the second rotational rate totransfer the second part of the fluid from the metering chamber throughthe valve.

In another embodiment the cartridge further comprises a fluid chamberfor receiving a fluid. The cartridge further comprises a fluid chamberduct connecting the fluid chamber and the aliquoting chamber. Fillingthe aliquoting chamber comprises filling the fluid chamber with thefluid. Filling the aliquoting chamber further comprises controlling therotational rate of the cartridge to transport the fluid from the fluidchamber to the aliquoting chamber via the fluid chamber duct.

In another aspect the invention, an embodiment provides for a cartridgefor an automatic analyzer. The cartridge is operable for being spunaround a rotational axis. The cartridge comprises an aliquoting chamber.The cartridge further comprises a metering chamber. The cartridgefurther comprises a connecting duct for connecting the metering chamberwith the aliquoting chamber. The connecting duct comprises a ductentrance in the aliquoting chamber. The connecting duct furthercomprises a duct exit in the metering chamber. A circular arc about therotational axis passes through both the duct entrance and the duct exit.The cartridge further comprises a downstream fluidic element. Thedownstream fluidic element is connected to the metering chamber via avalve. The cartridge further comprises a fluidic structure forprocessing a biological sample into the processed biological sample. Thefluidic structure comprises the downstream fluidic element. Thedownstream fluidic element is fluidically connected to the fluidicstructure. The fluidic structure comprises a measurement structure forenabling measurement of the processed biological sample. The fluidicstructure is configured for receiving the biological sample.

In another embodiment the cartridge further comprises an excess fluidchamber connected to the aliquoting chamber via a fluidic connection.The fluidic connection comprises a fluidic connection entrance. Thefluidic connection entrance is further away from the rotational axisthan the circular arc that passes through both the duct entrance and theduct exit. The fluidic connection entrance sets the maximum level of thefluid in the aliquoting chamber. The statement that the fluidicconnection entrance is further away from the rotational axis than thecircular arc that passes through both the duct entrance and the ductexit is equivalent to stating that the duct entrance is above themaximum fluid level in the aliquoting chamber. When the cartridge isrotating at a sufficiently large rotational rate the centrifugal forcewill keep the fluid in the aliquoting chamber and the maximum level willbe set by the fluidic connection entrance. Slowing the rate of therotation may cause the inertia of the fluid to cause it to move towardsthe duct entrance. This may then result in fluid being transferred tothe metering chamber.

In another embodiment the aliquoting chamber has a lower portion and anupper portion. The lower portion is further from the rotational axisthan the upper portion. A cross-sectional profile of the lower portiontapers away from the upper portion. In an embodiment the lower portionis defined by the duct entrance and its entry into the aliquotingchamber. Having the lower portion taper away from the upper portionmeans that the lower portion becomes more narrow as the distance fromthe rotational axis increases. This narrowing or tapering may be used toincrease the capillary force in the lower portion. The lower portion mayalso extend up to the connecting duct. This may provide a way forcapillary forces to direct fluid towards the metering chamber.

In another embodiment the lower portion is operable for causing fluid toflow into the connecting duct using capillary action. The taper maycause capillary forces. This may be used to direct fluid to theconnecting duct and thus ultimately to the metering chamber.

In another embodiment the connecting duct is operable for causing fluidto flow from the aliquoting chamber to the metering chamber usinginertia and capillary forces.

In another embodiment the aliquoting chamber has sidewalls. The sidewalllocated next to the metering chamber may have a tapered profile tocreate a capillary force which sucks or draws fluid into this area andassists in transporting fluid to the connecting duct and thus to themetering chamber.

In another embodiment the metering chamber has a metering chambersurface. A part of the metering chamber surface is rounded.

In another embodiment the entire surface of the metering chamber isrounded. It may be beneficial to have the surfaces of the meteringsurface rounded so that there are no sharp corners. This may help toeffectively transfer fluid to the metering chamber and to fill themetering chamber completely. For instance corners and other such areaswith narrow areas may trap bubbles. Having bubbles trapped in themetering chamber will effectively change the volume that the meteringchamber is able to transfer. Having a different number of bubbles orbubbles with different volumes at different times may result in aninconsistent amount of fluid being transferred by the metering chamberto the downstream fluidic element. Using these smooth surfaces withinthe metering chamber reduces the chances of bubbles thus providing formore consistent transfer of fluid to the downstream fluidic element.

In another embodiment the metering chamber has sidewalls and a centralregion. The sidewalls taper away from the central region. Having thesidewalls taper away from the central region may result in a largercapillary action near the sidewalls than in the central region area.This may cause the sidewalls to fill first with fluid and this mayreduce the chances of bubbles forming or adhering in the meteringchamber.

In other embodiments the metering chamber has sidewalls. A profile ofthe metering chamber tapers towards the sidewalls.

In another embodiment the capillary action next to the sidewalls of themetering chamber is greater than the capillary action in the centralregion of the metering chamber. This may result in the sidewalls fillingwith fluid before the central region.

In another embodiment the sidewalls are operable for filling with fluidbefore the central region to prevent the formation and/or adherence ofbubbles in the metering chamber.

In another embodiment the metering chamber is operable for causing fluidto fill the metering chamber using capillary action.

In another embodiment the connecting duct is operable for causing fluidto flow from the aliquoting chamber to the metering chamber usingcapillary action.

For example the connecting duct may have a depth 0.5 mm and a width inthe radial direction of 1 mm. The depth may also be greater than 0.2 mm.The width may also be greater than 0.2 mm.

In another embodiment the capillary action in the metering chamber isgreater than the capillary action in the connecting duct.

In another embodiment the capillary action in the connecting duct ishigher than the capillary action in the aliquoting chamber in particularthe lower portion of the aliquoting chamber.

In another embodiment the capillary action in the connecting duct ishigher than the capillary action in the lower portion of the aliquotingchamber and the capillary action in the lower portion of the aliquotingchamber is higher than the capillary action in the upper portion of thealiquoting chamber.

In another embodiment the cartridge further comprises an expansionchamber with a vent. The expansion chamber is fluidically connected tothe metering chamber. The capillary action in the metering chamber isgreater than the capillary action in the expansion chamber. Theexpansion chamber is nearer to the rotational axis than the meteringchamber. The use of such an expansion chamber may allow air to uniformlyexit the metering chamber. This may further reduce the chances ofbubbles forming or adhering in the metering chamber.

In another embodiment the metering chamber has an upper edge or surface.The upper edge or surface is the boundary of the metering chamber thatis closer to the rotational axis than the rest of the metering chamber.In this embodiment the whole upper section or boundary of the meteringchamber may open into the expansion chamber. This may further reduce thechances of bubbles forming or adhering when filling the meteringchamber.

In another embodiment the cartridge further comprises a fluid chamberfor receiving a fluid. The cartridge further comprises a fluid chamberduct connecting the fluid chamber and the aliquoting chamber.

In another embodiment the cartridge further comprises a reservoir filledwith the fluid. The reservoir is configured for being opened and fortransferring the fluid to the fluid chamber. The cartridge may have forexample a reservoir opening element that could be used for opening thereservoir. It may also be possible that an actuator could be used toactuate or activate the reservoir opening element. For instance anautomatic analyzer may have a device which would cause the actuation ofthe reservoir or a mechanism attached to it in order to open thereservoir allowing the fluid contained in the reservoir to be enteredinto the fluid chamber.

The reservoir may for example be sealed with a removable or pierceableseal that could for example be a thin film or a foil. For example asmall piece of metal foil or a thin film of plastic may be used as apierceable seal. The fluid chamber or another component of the cartridgemay have a piercing structure for opening the pierceable seal. Thepiercing structure may be any structure which is capable of piercing theparticular pierceable seal and for instance could be a pin, a lance, ora sharp edge. In other examples the removable seal may be able to bepeeled off to open the reservoir.

In another embodiment the fluid chamber or a fluid receiving structureconnected to the fluid chamber is configured for receiving a dosingneedle for dispensing the fluid to the fluid chamber. This for instancemay be performed manually or an automatic analyzer may have a dosingneedle which automatically dispenses fluid to the fluid chamber or thefluid receiving structure.

In another embodiment the fluid is any one of the following: adispersion, a fluid comprising nanoparticles, a fluid comprising a bloodgrouping reagent, a fluid comprising an immune reagent, a fluidcomprising an antibody, a fluid comprising an enzyme, a fluid comprisingone or more substrates for an enzymatic reaction, a fluid comprisingfluorescence emitting molecules, a fluid comprising molecules formeasuring immunochemical reactions, a fluid comprising molecules formeasuring reactions of nucleic acids, a fluid comprising a recombinantprotein, a fluid comprising virus isolate, a fluid comprising a virus, afluid comprising a biological reagent, a solvent, a diluent, a buffer, afluid comprising a protein, a fluid comprising a salt, a detergent, afluid comprising a fluid comprising a nucleic acid, a fluid comprisingan acid, a fluid comprising a base, an aqueous solution, a non-aqueoussolution, and combinations thereof.

In another embodiment the measurement structure comprises two or moreelectrodes and/or an optical measurement structure. The measurementsystem comprises a system for making an electrical measurement. Themeasurement system comprises a system for making optical measurements.

In some embodiments the optical measurement structure may be atransparent structure or an optically transparent structure. Themeasurement system comprises an optical measurement system.

In some examples optically transparent may include near infrared andnear ultraviolet. In other examples optically transparent may excludethe near infrared or near ultraviolet.

Some examples may have both the measurement structure with thetransparent structure and also the electrodes for more complicatedtests. For example the measurement structure may be a structure formaking electrochemiluminescence measurements where electrodes cause anoptical excitation in a sample.

In other examples the measurement structure comprises two or moreelectrodes for making an electrical measurement or ECL measurement ofthe processed biological sample. For example the measurement structuresof Martinez-Duarte et. al. or Kim et. al. may be incorporated into acartridge.

Examples may also only have electrode. For example in an electrochemicaldetection structure an electrode may be used to measure a current causedby the result of a enzymatic reaction.

In another aspect of the invention, an embodiment provides for anautomatic analyzer configured for receiving a cartridge according to anembodiment. The automatic analyzer comprises a cartridge spinner, ameasurement system, and a controller configured to control the automaticanalyzer. The cartridge spinner may be adapted for spinning thecartridge about the rotational axis.

The controller is configured or programmed to control the cartridgespinner to control the rotational rate of the cartridge to process thebiological sample into the processed biological sample using the fluidicstructure. This may involve rotating the cartridge at different ratesfor varying amounts of time to process the biological sample into theprocessed biological sample using the fluidic structure. The controlleris further configured or programmed to control the cartridge spinner todecrease the rotational rate of the cartridge to force the fluid in thereservoir into the connecting duct and to fill the metering chamber afirst time. The controller is further configured or programmed tocontrol the cartridge spinner to increase the rotational rate of thecartridge to transfer a first part of the fluid from the meteringchamber through a valve and to transfer a first remaining part back intothe aliquoting chamber.

The controller is further configured or programmed to control thecartridge spinner to decrease the rotational rate of the cartridge toforce the fluid in the reservoir into the connecting duct and to fillthe metering chamber a second time. The controller is further configuredor programmed to control the cartridge spinner to increase therotational rate of the cartridge to transfer a second part of the fluidfrom the metering chamber through the valve and to transfer a secondremaining part back into the aliquoting chamber. The controller isfurther configured or programmed to control the measurement system toperform the measurement using the measurement structure and using themeasurement system.

It is understood that one or more of the aforementioned embodiments ofthe invention may be combined as long as the combined embodiments arenot mutually exclusive.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following embodiments of the invention are explained in greaterdetail, by way of example only, making reference to the drawings inwhich:

FIG. 1 illustrates fluidic elements for performing multiple aliquots ofa fluid;

FIG. 2 illustrates a cross sectional view of a metering chamber;

FIG. 3 illustrates an example of a cartridge that incorporates thefluidic elements of FIG. 1;

FIG. 4 illustrates part of a method of performing a dispensing fluidusing the fluidic elements of FIG. 1;

FIG. 5 further illustrates part of a method of performing a dispensingfluid using the fluidic elements of FIG. 1;

FIG. 6 further illustrates part of a method of performing a dispensingfluid using the fluidic elements of FIG. 1;

FIG. 7 further illustrates part of a method of performing a dispensingfluid using the fluidic elements of FIG. 1;

FIG. 8 further illustrates part of a method of performing a dispensingfluid using the fluidic elements of FIG. 1;

FIG. 9 further illustrates part of a method of performing a dispensingfluid using the fluidic elements of FIG. 1;

FIG. 10 further illustrates part of a method of performing a dispensingfluid using the fluidic elements of FIG. 1;

FIG. 11 illustrates an example of an automatic analyzer; and

FIG. 12 shows a flow chart which illustrates a method of operating theautomatic analyzer of FIG. 11.

DETAILED DESCRIPTION

Like numbered elements in these figures are either equivalent elementsor perform the same function. Elements which have been discussedpreviously will not necessarily be discussed in later figures if thefunction is equivalent.

For heterogeneous immunochemical assays a washing buffer is oftenrequired to perform separation or washing steps to increase testsensitivity and reproducibility. For clinical chemistry tests buffersare often required for sample dilution or biochemical reactions.According to Richtlinie der Bundesärztekammer (RiliBÄK) guidelines forPoint of Care(POC) disposables all liquid reagents have to be pre-storedon the disposable. From such pre-storage containers, the released fluidvolume is typically released at once. If the fluid volume has to besplit into aliquots complicated space-consuming microfluidic structuresare required. This space consumption often hinders the implementation ofparallel microfluidic structure for panels into microfluidicdisposables.

Further, valves typically used for disc format disposables like siphons,geometrical valves or hydrophobic valves can either be used one timeonly or special variants of siphons can be used several times but afluid volume in the interconnected chamber is completely transferredthrough the valve without the possibility to split the volumes intoaliquots. Therefore with state-of-the art valves it is not possible torelease a fluid volume from a pre-storage containment into amicrofluidic cavity featuring a siphon valve and split this volume intoseveral aliquots.

A disadvantage with geometrical valves is that there is no control offluids with decreased surface tension is possible. This is especiallytrue for washing buffers.

A disadvantage with using hydrophobic valves is that there no control offluids with decreased surface tension is possible. This is especiallytrue for washing buffers. Hydrophobic valves also have the disadvantagethat they can only be used once.

A disadvantage of state of the art siphons is that state of the artsiphons can only be filled once. Air bubbles remaining in the siphonafter this has been used inhibit a second filling of the siphon. Furtherthe siphons will transfer the complete fluid volume located radiallyinwards of the siphon from an upstream chamber into a downstream fluidicelement.

FIG. 1 shows a number of fluidic components 100. The fluidic components100 are part of the fluidic components that make up a disc. There is arotational axis labeled 102. Also shown in the Fig. is a portion of afluid chamber 104. The fluid chamber either is designed for receivingfluid or for having a reservoir that provides fluid via a fluid chamberduct 106 that leads into the aliquoting chamber 108. In this example thealiquoting chamber 108 is well-shaped. There is a connecting duct 110which connects the aliquoting chamber 108 with a metering chamber 112.The connecting duct 110 has a duct entrance 114 and a duct exit 116. Theduct entrance 114 leads to the aliquoting chamber 108 and the duct exit116 leads to the metering chamber 112. A circular arc 118 that is drawnabout the rotational axis 102 passes both through the duct entrance 114and the duct exit 116. The metering chamber 112 is connected via a tube120 to a downstream fluidic element 122. In this example there is avalve 121 between the tube 120 and the metering chamber 112. In thisexample the valve 121 is a capillary valve.

The valve 121 could be implemented in different ways. In somealternatives the tube 120 could function as a capillary valve.Alternatively a valve could be placed between the elements 120 and 122.In other embodiments a duct could be connected in the same location anda controllable microvalve could be used instead. The controllablemicrovalve could be placed between the metering chamber 112 and the tube120 or between the tube 120 and the downstream fluidic element 122.

An optional expansion chamber 124 is shown as bordering on an upper edge126 of the metering chamber 112. There is a vent 128 which vents theexpansion chamber 124. The whole boundary between the metering chamber112 and the expansion chamber 124 is open. This may help reduce thechances of bubbles forming in the metering chamber 112. In some examplesthe expansion chamber 124 may have a thickness which is greater thanthat of the metering chamber 112. Capillary forces may be used then tokeep the fluid in the metering chamber 112. The dashed line labeled 130and also A-A shows the location of a cross-sectional view of themetering chamber 112. This cross-sectional view is shown in FIG. 2. Thealiquoting chamber 108 can be shown as also having a vent 128. Theregion around the duct entrance 114 is in this embodiment funnel-shaped.It may also be noted that the aliquoting chamber 108 is shown as nothaving sharp edges. The lack of sharp edges helps to facilitate themovement of fluid from the aliquoting chamber 108 to the duct entrance114 when the disc is decelerated.

The aliquoting chamber 108 is also shown as having a connection to afluidic connection 134 which leads to an excess fluid chamber 132. Thefluidic connection 134 has a fluidic connection entrance 136. Thefluidic connection entrance 136 defines the maximum fluid level in thealiquoting chamber 108. The maximum fluid level in the aliquotingchamber 108 is lower than the circular arc 118. The fluidic connection134 is connected to the excess fluid chamber 132 via a capillary valve138 in this embodiment. The use of a valve or a capillary valve isoptional. The excess fluid chamber is shown as having a vent 128 and itis also connected to a failsafe chamber 140. When the fluid flows intothe excess fluid chamber 132 the failsafe chamber 140 is filled. Thefailsafe chamber 140 may be used to indicate if fluid has entered theexcess fluid chamber 132 optically. For example during use if thefailsafe chamber 140 is not filled it may indicate that the aliquotingchamber 108 was not properly filled with fluid.

FIG. 2 shows a cross-sectional view 200 of the profile A-A which islabeled 130 in FIG. 1. In this Fig. the body of the cartridge 202 can beseen. There is an opening in the body 202 for the metering chamber 112.The body of the cartridge 202 in this example is fabricated by injectionmolding. The body of the cartridge is assembled from a lid 208 and asupport structure 210.

At the far end of the metering chamber the entrance into the valve 121can be seen. The metering chamber 112 can be seen as being divided intoseveral different regions. On the edges there are two sidewalls regions204. Between the two sidewalls regions or two side regions is a centralregion 206. The sidewall 204 regions become more narrow or taper awayfrom the central region 206. This causes a narrowing in the dimensionsof the metering chamber 112 in this region. The capillary action maytherefore be higher in the sidewall regions 204 than in the centralregion 206. This may cause the metering chamber 112 to fill with fluidfirst in the sidewall region before the central region 206. This mayhave the benefit of using a number of bubbles which are formed ortrapped in the metering chamber 112 when the metering chamber 112 isfilled with fluid.

FIG. 3 shows the integration of the fluidic components 100 into acartridge 300. The cartridge 300 is flat and disc-like and is shown ashaving a rotational axis 102. There is a fluid chamber 104 which isadapted or operable for receiving a fluid. The fluid reservoir 306filled with a fluid 307 is sealed with a pierceable seal 308 in thisexample and there is a piercing element 310 on the wall of the fluidchamber 104. The fluid reservoir has a number of engaging surfaces orreservoir opening elements 312 which may be manipulated manually or byan apparatus such as an actuator which causes the pierceable seal 308 tocontact the piercing element 310. This then causes the fluid chamber 104to fill with the fluid 307. The fluid chamber 104 is shown as beingconnected to a first duct 106. The first duct 106 is connected to analiquoting chamber 108. When the disc 300 is rotated about therotational axis 102 centrifugal force forces fluid 307 through the duct106. This then causes the aliquoting chamber 108 to fill with the fluid307.

The aliquoting chamber 108 is shown as being connected to second duct110 which leads to the metering chamber 112 as is shown in FIG. 1. Inthis example the aliquoting chamber 108 is laid out in a plane-likefashion aligned with the plane of the disc. The rotational axis isperpendicular to the plane. Attached to the aliquoting chamber 108 is anexcess fluid container 132. This is an optional element.

The metering chamber 112 is shown as being connected to a downstreamfluidic element 122 via a tube 120. A valve 121 is positioned betweenthe metering chamber 112 and the tube 120. The downstream fluidicelement 122 is part of a fluidic structure 336 for processing abiological sample into a processed biological sample.

The fluidic structure 336 comprises a number of fluidic elements 338that are connected by various ducts and siphons 340. There are also anumber of vents 342 within the fluidic structure 336. In this examplethere is an opening 346 which enables a biological sample to be placedinto the fluidic structure 336. There is also a cover lid 348 which isused to close and seal the opening 346. The fluidic structure 336 alsocomprises a measurement structure 344 which allows a measurement to bemade on the biological sample using a measurement system.

The measurement system may for instance be an optical, electrical, or acombination of the two system for making the measurement on theprocessed biological sample.

The processing of the biological sample can be controlled by controllingthe rotational rate about the rotational axis and duration. The siphons340 are designed to be filled automatically using a capillary action.However, a sufficiently large rotational rate about the rotational axis102 will produce a centrifugal force which will oppose the capillaryaction. Thus, by controlling the rotational rate and the duration ofrotation at particular rates the processing of the biological sample canbe controlled. In a typical usage the biological sample may be placedinto the inlet 346 and the rotation rate of the system may becontrolled. Then at some point an actuator or other mechanical means isused to manipulate the reservoir opening element and causes the piercingelement 310 to pierce the pierceable seal 308. Rotation can then forcefluid into the aliquoting chamber and a variety of rotational rates maybe used to perform multiple aliquotations using the cartridge 300.

FIGS. 4-10 illustrate how the fluidic components 100 may be used toperform multiple aliquotations of fluid to the downstream fluidicelement 122.

In FIG. 4 the disc is rotated about the axis of rotation 102 in thedirection indicated by the arrow 400. The arrow 400 indicates thedirection of rotation. In this particular example the disc is spinningat 20 Hz. Fluid is transported into the aliquoting chamber 108 from thefluid chamber 104. Fluid 307 can be seen dripping from the fluid chamberduct 106 into the aliquoting chamber 108. The fluid volume in thealiquoting chamber 108 is limited and thereby metered by the fluidicconnection 134 which connects to the excess fluid chamber 132. Thefailsafe chamber 140 can be seen as being filled with fluid.

Next in FIG. 5 the fluid volume 307 has been completely transferred fromthe fluid chamber 104 into the aliquoting chamber 108. The failsafechamber 140 is shown as being filled with the fluid. In this example thedisc is still spinning at the same rate as was shown in FIG. 4. Thealiquoting chamber 108 is filled with fluid 307 up to the maximum fluidlevel 500. It can be seen that the maximum fluid level 500 is below orfurther away from the axis of rotation 102 than the connecting duct 110.When the disc is spinning in this way the fluid 307 cannot enter themetering chamber 112.

Next in FIG. 6 the disc stops with a high rate of deceleration forexample at 50 Hz per second. The inertia of the fluid forces the fluid307 towards and through the connecting duct 110 and into the meteringchamber 112. It can be seen in this Fig. that the fluid 307 is fillingthe sides of the metering chamber 112 before it is filling the centralregion. This is because of the tapered like structures 204 shown in FIG.2. Capillary action causes this portion of the metering chamber 112 tofill first. This manner of filling the metering chamber may reduce thechances that air bubbles form or adhere in the metering chamber 112.

In FIG. 7 the cartridge is still stationary or at a reduced rotationrate and the metering chamber 112 is completely filled with fluid 307.The cartridge or disc may still be considered to be at rest. Thecomplete filling of the metering chamber is caused by capillary forcescaused by the respective geometrical dimensions of the metering chamber.

FIG. 8 shows the same view as is shown in FIG. 7 except a dashed line800 has been drawn in the metering chamber 112. This line 800 in themetering chamber 112 divides the fluid in the metering chamber intoseveral parts or portions. The fluid part 804 radially inward (closer toaxis of rotation 102) from the line 800 may flow back into thereservoir. The radially outward part (further from the axis of rotation102) or part 802 may be completely transferred into the fluidic element122. The radially inward part 804 can be referred to as the remainingpart of the fluid and the radially outward part 802 can be referred toas the part of the fluid 802 that is transferred into the downstreamfluidic element. The volume of the fluid 802 is the aliquot transferredin a subsequent step to the downstream fluidic element 122

Next in FIG. 9 the disc begins to accelerate and spin around in thedirection 400. The disc for instance may spin at the rate shown in FIGS.1 and 2. The disc accelerates; this causes the capillary valve 121 toopen. The remaining part of the fluid 804 was transferred back to thealiquoting chamber 108. The part of the fluid 802 is in the process ofbeing transferred to the downstream fluidic element 122. A drop of thefluid can be seen dropping from the tube 120.

Next in FIG. 10 it can be seen that the fluid volume 802 has beencompletely transferred to the downstream fluidic element 122 and is nolonger visible in the Fig. The remaining part of the fluid 804 has beentransferred into the aliquoting chamber 108 and is mixed with the fluid307. The first aliquotion step is finished; the process may be repeatedagain from FIG. 6 and may be repeated until the fluid volume 307 in thealiquoting chamber 108 is smaller than the volume of the meteringchamber 112.

FIG. 11 shows an example of an automatic analyzer. The automaticanalyzer 1100 is adapted for receiving a cartridge 300. There is acartridge spinner 1102 which is operable for rotating the cartridge 300about the rotational axis 102. The cartridge spinner 1102 has a motor1104 attached to a gripper 1106 which attaches to a portion of thecartridge 1108. The cartridge 300 is shown further as having ameasurement or transparent structure 1110. The cartridge 300 can berotated such that the measurement structure 1110 goes in front of ameasurement system 1112 which can perform for example an opticalmeasurement on the processed biological sample. The actuator 1104 as wasshown previously is also shown in this Fig. It can be used to open afluid reservoirs in the cartridge 100. In some examples the actuator maybe replaced with a dispenser with a dosing needle for filling the fluidchamber of the cartridge 300.

The actuator 1111, the cartridge spinner 1102, and the measurementsystem 1112 are shown as all being connected to a hardware interface1116 of a controller 1114. The controller 1114 contains a processor 1118in communication with the hardware interface 1116, electronic storage1120, electronic memory 1122, and a network interface 1124. Theelectronic memory 1130 has a machine executable instructions whichenables the processor 1118 to control the operation and function of theautomatic analyzer 1100. The electronic storage 1120 is shown ascontaining a measurement 1132 that was acquired when instructions 1130were executed by the processor 1118. The network interface 1124 enablesthe processor 1118 to send the measurement 1132 via network interface1126 to a laboratory information system 1128.

FIG. 12 shows a flowchart which illustrates a method of operating theautomatic analyzer 1100 shown in FIG. 11. First in step 1200 theprocessor 118 controls the cartridge spinner 1102 to control therotational rate of the cartridge to process the biological sample intothe processed biological sample using the fluidic structure. Next instep 1202 the processor 1108 controls the cartridge spinner 1102 todecrease the rotational rate of the cartridge to force fluid in thealiquoting chamber into the connecting duct and to fill the meteringchamber 112 for a first time. Next in step 1204 the processor 1108controls the cartridge spinner 1102 to increase the rotational rate ofthe cartridge 300 to transfer a first part of the fluid from themetering chamber through the valve and to transfer a first remainingpart back into the aliquoting chamber 108. Next in step 1206 theprocessor controls the cartridge spinner to increase the rotational rateof the cartridge to force the fluid in the reservoir into the connectingduct 110 and to fill the metering chamber 112 a second time. Next theprocessor controls the cartridge spinner to increase the rotational rateof the cartridge 300 to transfer a second part of the fluid from themetering chamber through the valve and to transfer a second remainingpart back into the aliquoting chamber. Finally in step 1210 theprocessor controls the measurement system 112 to perform the measurementin the measurement structure 110.

LIST OF REFERENCE NUMERALS

-   -   100 fluidic components    -   102 rotational axis    -   104 fluid chamber    -   106 fluid chamber duct    -   108 aliquoting chamber    -   110 connecting duct    -   112 metering chamber    -   114 duct entrance    -   116 duct exit    -   118 circular arc    -   120 tube    -   121 valve    -   122 downstream fluidic element    -   124 expansion chamber    -   126 upper edge    -   128 vent    -   130 profile A-A    -   132 excess fluid chamber    -   134 fluidic connection    -   136 fluidic connection entrance    -   138 capillary valve    -   140 fail safe chamber    -   200 cross sectional view A-A    -   202 body of cartridge    -   204 side walls    -   206 central region    -   208 lid    -   210 support structure    -   300 cartridge    -   306 fluid reservoir with fluid    -   307 fluid    -   308 pierceable seal    -   310 piercing element    -   312 engaging surface or reservoir opening element    -   336 fluidic structure    -   338 fluidic element    -   340 siphon    -   342 vent    -   344 measurement structure    -   346 opening    -   348 cover lid    -   400 direction of rotation    -   500 maximum fluid level    -   800 dividing line    -   802 part of fluid    -   804 remaining part of fluid    -   1100 automatic analyzer    -   1102 cartridge spinner    -   1104 motor    -   1106 gripper    -   1108 portion of cartridge    -   1110 measurement structure    -   1111 actuator    -   1112 measurement system    -   1114 controller    -   1116 hardware interface    -   1118 processor    -   1120 electronic storage    -   1122 electronic memory    -   1124 network interface    -   1126 network connection    -   1128 laboratory information system    -   1130 executable instructions    -   1132 measurement    -   1200 control the rotational rate of the cartridge to process the        biological sample into the processed biological sample using the        fluidic structure    -   1202 decrease the rotational rate of the cartridge to force the        fluid in the aliquoting chamber into the connecting duct and to        fill the metering chamber a first time    -   1204 increasing the rotational rate of the cartridge to transfer        a first part of the fluid from the metering chamber through the        valve and to transfer a first remaining part back into the        aliquoting chamber    -   1206 decrease the rotational rate of the cartridge to force the        fluid in the aliquoting chamber into the connecting duct and to        fill the metering chamber a second time    -   1208 increase the rotational rate of the cartridge to transfer a        second part of the fluid from the metering chamber through the        valve and to transfer a second remaining part back into the        aliquoting chamber    -   1210 control the measurement system to perform the measurement        using the measurement structure and using a measurement system

What is claimed is:
 1. A method of aliquoting a fluid using a cartridge,wherein the cartridge is operable for being spun around a rotationalaxis, wherein the cartridge comprises: an aliquoting chamber; a meteringchamber, wherein the metering chamber has side wall regions and acentral region, wherein the side wall regions are narrower than thecentral region in a cross sectional view of the metering chamber,wherein capillary action next to the side wall regions of the meteringchamber is greater than in the central region of the metering chamber; aconnecting duct for connecting the metering chamber with the aliquotingchamber, wherein the connecting duct comprises a duct entrance in thealiquoting chamber, wherein the connecting duct further comprises a ductexit in the metering chamber, wherein a circular arc about therotational axis passes through both the duct entrance and the duct exit;a vent, wherein the vent is connected to the metering chamber, whereinthe vent is nearer to the rotational axis than the metering chamber; anda valve connected to the metering chamber, wherein the method comprisesthe steps of: filling the aliquoting chamber with a fluid; rotating thecartridge at a rotational rate to permit the fluid in the aliquotingchamber to flow into the connecting duct and to fill the meteringchamber a first time; increasing the rotational rate of the cartridge totransfer a first part of the fluid from the metering chamber through thevalve and to transfer a first remaining part back into the aliquotingchamber; decreasing the rotational rate of the cartridge to permit thefluid in the aliquoting chamber to flow into the metering chamber and tofill the metering chamber a second time; and increasing the rotationalrate of the cartridge to transfer a second part of the fluid from themetering chamber through the valve and to transfer a second remainingpart back into the aliquoting chamber.
 2. The method of claim 1, whereinincreasing the rotational rate of the cartridge to transfer the firstpart of the fluid from the metering chamber through the valve comprisesincreasing the rotational rate of the cartridge to a first rotationalrate to transfer the first remaining part of the fluid back to thealiquoting chamber and increasing the rotational rate of the cartridgeto a second rotational rate to transfer the first part of the fluid fromthe metering chamber through the valve.
 3. The method of claim 1,wherein the step of increasing the rotational rate of the cartridge totransfer the second part of the fluid from the metering chamber throughthe valve comprises increasing the rotational rate of the cartridge to afirst rotational rate to transfer the second remaining part of the fluidback to the aliquoting chamber and increasing the rotational rate of thecartridge to a second rotational rate to transfer the second part of thefluid from the metering chamber through the valve.
 4. The method ofclaim 1, wherein the cartridge further comprises a fluid chamber forreceiving the fluid, wherein the cartridge further comprises a fluidchamber duct connecting the fluid chamber and the aliquoting chamber,wherein filling the aliquoting chamber comprises: filling the fluidchamber with the fluid; and controlling the rotational rate of thecartridge to transport the fluid from the fluid chamber to thealiquoting chamber via the fluid chamber duct.
 5. The method of claim 1,wherein the cartridge further comprises an excess fluid chamberconnected to the aliquoting chamber via a fluidic connection, whereinthe fluidic connection comprises a fluidic connection entrance, whereinthe fluidic connection entrance is further away from the rotational axisthan the circular arc that passes through both the duct entrance and theduct exit.
 6. The method of claim 1, further comprises flowing fluidfrom the aliquoting chamber to the metering chamber using capillaryaction.
 7. The method of claim 1, further comprises filling areas nextto the side wall regions of the metering chamber with the fluid beforethe central region to prevent formation and/or adherence of bubbles inthe metering chamber.
 8. A cartridge operable for being spun around arotational axis, wherein the cartridge comprises: an aliquoting chamber;a metering chamber, wherein the metering chamber has side wall regionsand a central region, wherein the side wall regions are narrower thanthe central region in a cross sectional view, wherein capillary actionnext to the side wall regions of the metering chamber is greater than inthe central region of the metering chamber; a connecting duct forconnecting the metering chamber with the aliquoting chamber, wherein theconnecting duct comprises a duct entrance in the aliquoting chamber,wherein the connecting duct further comprises a duct exit in themetering chamber, wherein a circular arc about the rotational axispasses through both the duct entrance and the duct exit; a valveconnected to the metering chamber; and a vent, wherein the vent isconnected to the metering chamber, wherein the vent is nearer to therotational axis than the metering chamber.
 9. The cartridge of claim 8,wherein the cartridge further comprises an excess fluid chamberconnected to the aliquoting chamber via a fluidic connection, whereinthe fluidic connection comprises a fluidic connection entrance, whereinthe fluidic connection entrance is further away from the rotational axisthan the circular arc that passes through both the duct entrance and theduct exit.
 10. The cartridge of claim 8, wherein the aliquoting chamberhas a lower portion and an upper portion, wherein the lower portion isfurther from the rotational axis than the upper portion, wherein a crosssectional profile of the lower portion tapers away from the upperportion.
 11. The cartridge of claim 8, wherein the aliquoting chamberhas an aliquoting chamber surface, wherein a part of the aliquotingchamber surface near the duct is rounded.
 12. The cartridge of claim 8,wherein the connecting duct is configured to cause fluid to flow fromthe aliquoting chamber to the metering chamber using capillary action.13. The cartridge of claim 8, wherein the cartridge further comprises anexpansion chamber, wherein the vent is within the expansion chamber,wherein the expansion chamber is connected to the metering chamber,wherein capillary action in the metering chamber is greater thancapillary action in the expansion chamber, wherein the expansion chamberis nearer to the rotational axis than the metering chamber.
 14. Thecartridge of claim 8, further comprising: a fluid chamber for receivinga fluid; and a fluid chamber duct connecting the fluid chamber and thealiquoting chamber.
 15. The cartridge of claim 8, further comprising ameasurement structure with two or more electrodes and/or an opticalmeasurement structure, the measurement structure being fluidicallyconnected to the valve.
 16. A device configured for receiving acartridge according to claim 8, wherein the device comprises a cartridgespinner and a controller configured to control the cartridge spinner,wherein the controller is configured to: control the cartridge spinnerto rotate the cartridge at a rotational rate; control the cartridgespinner to decrease the rotational rate of the cartridge to permit thefluid in the reservoir into the connecting duct and to fill the meteringchamber a first time; control the cartridge spinner to increasing therotational rate of the cartridge to transfer a first part of the fluidfrom the metering chamber through the valve and to transfer a firstremaining part back into the aliquoting chamber; control the cartridgespinner to decrease the rotational rate of the cartridge to permit thefluid in the reservoir into the connecting duct and to fill the meteringchamber a second time; and control the cartridge spinner to increase therotational rate of the cartridge to transfer a second part of the fluidfrom the metering chamber through the valve and to transfer a secondremaining part back into the aliquoting chamber.